A particle-into-liquid collector for rapid measurement of aerosol bulk chemical composition

We report on a new instrument developed for rapid automated on-line and continuous measurement of ambient aerosol bulk composition. The general approach is based on earlier devices (Khlystov et al. 1995; Simon and Dasgupta 1995) in which ambient particles are mixed with saturated water vapor to produce droplets easily collected by inertial techniques. The resulting liquid stream is an ah-zed with an ion chromatograph to quantitatively measure the bulk aerosol ionic components. In this instrument, a modified version of a particle size magnifier (Okuyama et al. 1984) is employed to activate and grow particles comprising the fine aerosol mass. A single jet inertial impactor is used to collect the droplets onto a vertical glass plate that is continually washed with a constant water diluent flow of nominally 0.10 ml min(-1). The flow is divided and then analyzed by a dual channel ion chromatograph. In its current form, 4.3 min integrated samples were measured every 7 min. The instrument provides bulk composition measurements with a detection limit of approximately 0.1 mug m(-3) for chloride, nitrate, sulfate, sodium, ammonium, calcium, and potassium. Results obtained during its deployment in the August 1999 Atlanta EPA Supersite study are presented.